Study of the dissolution and growth of salt single crystals in inhomogeneous acoustic fields: I. A standing acoustic wave

The growth of the isolated (100) face of a KDP crystal at exposure of the phase boundary to the initial ultrasound field and a standing acoustic wave has been investigated. A significant growth response of this face, exposed to sound normally along the acoustic axis in the near zone of a piston-like half-wave vibrator with f = 20 kHz and tangentially in the pulsed two-frequency (f = 600 and 900 kHz) standing-wave mode, has been revealed. It is shown that the mechanisms of mass exchange enhancement in these acoustic modes are different. The results obtained show a fundamental possibility of controlling crystal growth and dissolution by varying the parameters of inhomogeneous acoustic field.     

Doping of KDP single crystals with cerium: Growth and optical properties

The features of doping of KDP crystals with cerium ions and organocerium complexes with alizarin complexon and arsenazo III have been investigated. It is established that “direct” doping by introducing cerium salts into the initial solution cannot be implemented. The effect of organometallic complexes of cerium on the crystal growth has been studied. Organocerium complexes predominantly enter the prismatic or pyramidal growth sectors. It is shown that the complex arsenazo III + Ce blocks the growth of the prismatic sector. Cerium-doped KDP crystals exhibit a photoluminescence band peaking at the wavelength λ_max= 350 nm.     

Effect of oxygen deficit and nonuniform distribution of technological impurities on the dielectric properties of Y3Fe5O12 crystals

The experimental and calculated values of the optical permittivity ε_∞ have been analyzed and generalized with allowance for the oxygen concentration and possible valences of Fe and O ions in YIG single crystals. It is shown that the deficit of oxygen ions in the samples is accompanied by a decrease in ε_∞. A decrease in the gradient of distribution of Ba ions over the sample thickness decreases the difference between the calculated and experimental values. It is revealed that the ratio of the number of valence electrons to the number of core electrons, with regard to their polarizabilities, is proportional to the ratio of the incoherent and coherent X-ray scattering intensities, nk/k.     

4-Functionally-substituted 3-heterylpyrazoles: XIX. 3-aryl-4-(5-isoxazolyl)pyrazoles

Oximes of 4-(4-pyrazolyl)-3-buten-2-onees obtained by successive reaction of 3-aryl-4-formylpyrazoles with acetone and hydroxylamine at the treatment with iodine suffered an oxidative cyclization yielding 3-aryl-4-(5-isoxazolyl)pyrazoles.     

Decrease in the group velocity of a light pulse in the Bose-Einstein condensate of a dilute gas

A semiclassical theory of electromagnetically induced transparency in a Bose-Einstein condensate is considered. A nonlinear Schrödinger equation that describes the interaction of the Bose-Einstein condensate with an electromagnetic field is derived. An analysis of the obtained solutions to this equation demonstrates a decrease in the group velocity of the light pulse.     

On a certain nonlocal problem for a hyperbolic equation

The author proves the existence and uniqueness of a generalized solution of a nonlocal problem with an integral condition for a hyperbolic equation with n spatial variables. This work is a continuation of the studies started in [3–5], where the solvability problem of nonlocal problems with an integral condition was studied for hyperbolic equations on the plane. __________ Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 33, Suzdal Conference-2004, Part 1, 2005.     

Diffuse x-ray scattering study of the formation of microdefects in heat-treated dislocation-free large-diameter silicon wafers

Diffuse x-ray scattering (DXS) is used to study the formation of microdefects (MDs) in heat-treated dislocation-free large-diameter silicon wafers with vacancies. The DXS method is shown to be efficient for investigating MDs in silicon single crystals. Specific defects, such as impurity clouds, are found to form in the silicon wafers during low-temperature annealing at 450°C. These defects are oxygen-rich regions in the solid solution with diffuse coherent interfaces. In the following stages of decomposition of the supersaturated solid solution, oxide precipitates form inside these regions and the impurity clouds disappear. As a result of the decomposition of the supersaturated solid solution of oxygen, interstitial MDs form in the silicon wafers during multistep heat treatment. These MDs lie in the {110} planes and have nonspherical displacement fields. The volume density and size of MDs forming in the silicon wafers at various stages of the decomposition are determined.     

Convergence of optimal controls in some optimization problems

We consider the behavior of bundles of optimal controls when the initial state of the system goes to some given vector. We investigate three types of optimization problems: problems with fixed process length and a free right endpoint; problems with fixed process length and a fixed right endpoint; time-optimal problems. The article is a review of recent results obtained by the author. __________ Translated from Nelineinaya Dinamika i Upravlenie, No. 4, pp. 301–314, 2004.